**Casio fx-991CW: Input Output Formats**

**The
Four Formats**

There are four input/output formats that the Casio fx-991CW has. With each mode, I will show three example problems and the default format the of the output. If you always want Decimal approximations, I would suggest setting the calculator to either MathI/DecimalO or LineI/DecimalO settings.

To set the input/output:

1. Press [ SETTINGS ].

2. Select Calc Settings and press either [ EXE ], [ OK ], or [ → ].

3. Select Input/Output and press either [ EXE ], [ OK ], or [ → ].

4. Select a format and press either [ EXE ] or [ OK ]. The circle next to the mode selected will be filled.

5. To quickly return the home screen, press [ AC ].

__MathI/MathO:
Math Input/Math Output__

Expressions are entered and displayed as written in textbook fashion. The fx-991CW returns results in exact form whenever possible in terms of π, square roots, and fractions. To get decimal approximations, press [ FORMAT ] and select Decimal.

Default (Radians Mode):

4 / 5 + 3 / 8 returns 47 / 40

√440 returns 2 × √110

cos^-1(0.5) returns 1 / 3 × π

__MathI/DecimalO:
Math Input/Decimal Ouptut__

Expressions are entered and displayed as written in textbook fashion. However, in this mode, the fx-991CW always returns the results as decimal expressions. You can still ask for exact answers, whenever possible, by pressing [ FORMAT ] and selecting Standard.

Default (Radians Mode):

4 / 5 + 3 / 8 returns 1.175

√440 returns 20.97617696

cos^-1(0.5) returns 1.04719551

__LineI/LineO:
Line Input/Line Output__

Expressions are entered in one-line format, similar to classic computers and calculators. Results, when possible and when fractions are used, are returned using fractions. Otherwise, all other results are returned in decimal approximation. To get decimal approximations on fractions, press [ FORMAT ] and select Decimal.

Default (Radians Mode):

4 / 5 + 3 / 8 returns 47 / 40

√440 returns 20.97617696

cos^-1(0.5) returns 1.04719551

__LineI/DecimalO:
Line Input/Decimal Output__

Expressions are entered in one-line format, similar to classic computers and calculators. However, in this mode, the fx-991CW always returns the results as decimal expressions. To see if the approximation can be converted to fractions (within the limitation of the calculator) press [ FORMAT ] and select Standard.

Default (Radians Mode):

4 / 5 + 3 / 8 returns 1.175

√440 returns 20.97617696

cos^-1(0.5) returns 1.04719551

I hope you find this helpful. Until next time,

Eddie

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